Prevalencia y caracterización genotípica de cepas de Staphylococcus aureus resistente a meticilina aisladas en un hospital regional mexicano / Prevalence and genotypic characterization of methicillin-resistant strains of Staphylococcus aureus isolated in a Mexican regional hospital

Resumen Introducción: Staphylococcus aureus es uno de los patógenos con mayor prevalencia en el mundo, asociado a una alta tasa de mortalidad y un rápido desarrollo de resistencia a los antimicrobianos. A pesar de su patogenicidad, su seguimiento epidemiológico en México es escaso. Objetivo: Analizar la epidemiología molecular local y determinar el origen clonal de cepas resistentes a meticilina (RM) aisladas de pacientes internados en el Hospital Central "Dr. Ignacio Morones Prieto". Métodos: Se llevó a cabo un estudio prospectivo de corte transversal, de julio a diciembre de 2016. La caracterización de las cepas se realizó mediante genotipificación Spa, la determinación por RPC punto final de la frecuencia de genes de virulencia específicos y su antibiograma. Resultados: A partir de estos datos, se obtuvo que la prevalencia de S. aureus RM fue de 25,7%, destacando la presencia del tipo Spa t895 en 76% de las cepas resistentes y un patrón similar de susceptibilidad a antimicrobianos. Conclusión: Los resultados de este estudio indican que la prevalencia regional de SARM no se ha modificado en los últimos 10 años y proporcionan información valiosa del origen clonal y los factores de virulencia de las cepas de S. aureus aisladas en la región.

Abstract Background: Staphylococcus aureus is one of most prevalent pathogens in the world associated with a high mortality rate and a rapid development of resistance to antibiotics. Despite its pathogenicity, epidemiological monitoring in Mexico is scarce. Aim: To analyze the local molecular epidemiology and determine the clonal origin of methicillin-resistant (MR) strains isolated from patients admitted to Hospital "Dr. Ignacio Morones Prieto". Methods: A cross-sectional prospective study was carried out from July to December 2016. The characterization of the strains was carried out by Spa genotyping, frequency of specific virulence genes by PCR and antibiogram. Results: The prevalence of MRSA was 25.7%, highlighting the presence of the Spa type t895 in 76% of the resistant strains and a similar pattern of susceptibility to antibiotics. Conclusion: The results of this study indicate that the regional prevalence of MRSA has not changed in the last 10 years and provide valuable information on the clonal origin and the virulence factors of the strains of S. aureus isolated in the region.

Clonal clusters and virulence factors of methicillin-resistant Staphylococcus Aureus: Evidence for community-acquired methicillin-resistant Staphylococcus Aureus infiltration into hospital settings in Chennai, South India

Background and Objective: Staphylococcus aureus is one of the major pathogens of nosocomial infections as wells as community-acquired (CA) infections worldwide. So far, large-scale comprehensive molecular and epidemiological characterisation of S. aureus from very diverse settings has not been carried out in India. The objective of this study is to evaluate the molecular, epidemiological and virulence characteristics of S. aureus in both community and hospital settings in Chennai, southern India. Methods: S. aureus isolates were obtained from four different groups (a) healthy individuals from closed community settings, (b) inpatients from hospitals, (c) outpatients from hospitals, representing isolates of hospital–community interface and (d) HIV-infected patients to define isolates associated with the immunocompromised. Antibiotic susceptibility testing, multiplex polymerase chain reactions for detection of virulence and resistance determinants, molecular typing including Staphylococcal cassette chromosome mec (SCCmec) and agr typing, were carried out. Sequencing-based typing was done using spa and multilocus sequence typing (MLST) methods. Clonal complexes (CC) of hospital and CA methicillin-resistant S. aureus (MRSA) were identified and compared for virulence and resistance. Results and Conclusion: A total of 769 isolates of S. aureus isolates were studied. The prevalence of MRSA was found to be 7.17%, 81.67%, 58.33% and 22.85% for groups a, b, c and d, respectively. Of the four SCCmec types (I, III, IV and V) detected, SCCmec V was found to be predominant. Panton-Valentine leucocidin toxin genes were detected among MRSA isolates harbouring SCCmec IV and V. A total of 78 spa types were detected, t657 being the most prevalent. 13 MLST types belonging to 9 CC were detected. CC1 (ST-772, ST-1) and CC8 (ST238, ST368 and ST1208) were found to be predominant among MRSA. CA-MRSA isolates with SCCmec IV and V were isolated from all study groups including hospitalised patients and were found to be similar by molecular tools. This shows that CA MRSA has probably infiltrated into the hospital settings.

Molecular characteristics and virulence gene profiles of Staphylococcus aureus causing bloodstream infection

ABSTRACT Background: The rate of methicillin-resistant Staphylococcus aureus (MRSA) among the total of S. aureus isolates decreased to 35.3% in 2017 in China. It is unclear whether the molecular characteristics of S. aureus isolates have changed as the rate decreased. Objective: This study aimed to investigate the molecular characteristics and virulence genes profile of S. aureus isolates causing bloodstream infection and analyze the correlation between the prevalence rates of the common sequence types and MRSA. Methods: A total of 112 S. aureus strains from eight hospitals of four cities, including 32 MRSA isolates, were identified and evaluated through multilocus sequence typing, spa typing, and determination of virulence genes. Results: Twenty-five STs were identified, of which ST5 (21.4%) was the most prevalent, whereas the prevalence of ST239 correlated with the rate of MRSA among all S. aureus isolates. Forty-six spa types were identified, of which t2460 (14.3%) was the most common. clfa, hla, seb, fnbA and hlb were the prevailing virulence genes. 81.3% MRSA and 45.0% methicillin-sensitive S. aureus (MSSA) isolates harbored six or more tested virulence genes. ST5-t2460, seldom noted in bloodborne S. aureus isolates in China, was the most common clone. The prevalence of harboring six or more virulence genes in ST5-t2460 and ST188-t189 were 93.8% and 8.3%, respectively. Conclusion: ST5-t2460 was the most common clone in S. aureus causing bloodstream infection followed by ST188-t189, which had never been noted in China before. Moreover, ST5-t2460 harbored more virulence genes than ST188-t189, and the prevalence of ST239 clone decreased with the proportion of MRSA among all S. aureus isolates.

Molecular characterisation of Staphylococcus aureus using spa typing as a diagnostic tool in Haryana, India

Background: Staphylococcus aureus is one of the top six most common etiologic agents of nosocomial, community and livestock acquired bacterial infections. These infections although initially were described as a major problem in hospitals have now also become a serious threat in community not only in India but also worldwide. Its prevalence varies depending on the health-care setting, country or a particular region. Thus to better understand the epidemiology of methicillin-resistant S. aureus (MRSA) in a particular geographical location, it is important to study the variations in the population using molecular tools. Methods: This prospective study was carried out in the Department of Microbiology of Shree Guru Gobind Singh Tricentenary (SGT) Medical College. Staphylococcal protein A (spa) typing was done on 250 S. aureus isolates obtained from various clinical specimens including pus, wound swabs, urine, catheters, blood and cerebrosspinal fluid from both indoor and outdoor patients of SGT Hospital, Budhera, Gurgaon. Results: The selected region of the spa gene of all 250 isolates which includes 87 MRSA and 163 methicillin-susceptible S. aureus were amplified. The spa gene was detected in 248 out of 250 isolates (99.2%), whereas in 2 isolates (0.8%), it remained undetected and referred as non-typable isolates. The 248 S. aureus isolates were typed into 39 spa types, which clustered into six different spa clonal clusters and eight singletons. Conclusion: High diversity observed within S. aureus isolates indicated that many different strains circulate in the study region or in the hospital. The results would contribute in the understanding of epidemiology related to S. aureus spread and prevention.

Diversity of livestock associated methicillin-resistant Staphylococcus aureus

Objective To evaluate the diversity and molecular characteristics of livestock associated methicillin-resistant Staphylococcus aureus (S. aureus) in livestock animals, food of animal origin and the environment in the Czech Republic. Methods After having been primarily enriched in buffered peptone water, the samples were cultured on Baird–Parker agar. Presumptive colonies were sub-cultured to blood agar and assessed morphologically. Furthermore, presumptive Staphylococcus aureus colonies were confirmed by MALDI-TOF. Multiplex PCR, spa-typing, and MLST have been used to characterize the strains. Each mecA-positive Staphylococcus aureus isolates were examined against 14 different antimicrobials by using disk diffusion method. Results In this study, 13 different spa-types belonging to five sequence types (ST) were detected. Ninety four percent of tested strains belonged to CC/ST398 for which t011, t034, t2123 and t2346 were the vast major spa-types. In addition, non-ST398 clones such as CC1(t127), ST5(t3598), ST8(t064) and ST361(t315) were detected, which are known as human associated clones. Conclusions The diversity of livestock associated methicillin-resistant Staphylococcus aureus has grown, and detecting lineages of human origin in animals and vice-versa becomes more common. Thus, livestock animal and its products will be a potential for the evolvement of methicillin-resistant Staphylococcus aureus in human population. Monitoring of pigs as well as other food-producing animal species and their products is therefore recommended.

Diversity of livestock associated methicillin-resistant Staphylococcus aureus

OBJECTIVE@#To evaluate the diversity and molecular characteristics of livestock associated methicillin-resistant Staphylococcus aureus in livestock animals, food of animal origin and the environment in the Czech Republic.@*METHODS@#After having been primarily enriched in buffered peptone water, the samples were cultured on Baird-Parker agar. Presumptive colonies were sub-cultured to blood agar and assessed morphologically. Furthermore, presumptive Staphylococcus aureus colonies were confirmed by MALDI-TOF. Multiplex PCR, spa-typing, and MLST have been used to characterize the strains. Each mecA-positive Staphylococcus aureus isolates were examined against 14 different antimicrobials by using disk diffusion method.@*RESULTS@#In this study, 13 different spa-types belonging to five sequence types (ST) were detected. Ninety four percent of tested strains belonged to CC/ST398 for which t011, t034, t2123 and t2346 were the vast major spa-types. In addition, non-ST398 clones such as CC1(t127), ST5(t3598), ST8(t064) and ST361(t315) were detected, which are known as human associated clones.@*CONCLUSIONS@#The diversity of livestock associated methicillin-resistant Staphylococcus aureus has grown, and detecting lineages of human origin in animals and vice-versa becomes more common. Thus, livestock animal and its products will be a potential for the evolvement of methicillin-resistant Staphylococcus aureus in human population. Monitoring of pigs as well as other food-producing animal species and their products is therefore recommended.

Characteristics, Detection And Typing Methods Of Community Acquired Methicillin Resistant Staphylococcus Aureus (CA-MRSA) – A Review

@#Staphylococcus aureus aregram positive cocci which colonizethe skin and mucous membranes particularly the anterior nares. Prevalence of nosocomial infections associated with methicillin resistant S. aureus have been reported in hospitals (HA-MRSA) for over five decades. Recently,community-acquired MRSA (CA-MRSA) has emerged as a cause of skin and soft tissue infections in healthy individuals. These strains are sensitive to antimicrobials, carry genes for Panton-Valentine leukocidin (PVL) toxin and belong to the staphylococcal cassette chromosome (SCC) mec type IV or V. The suspected mode of transmission involves close contact with carriers leading to skin or nasal colonization that resultin subsequent active infection. Molecular typing is used to determine the mode of transmission of CA-MRSA in the community.General typing methods such as pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) and specific methods for Staphylococci such as SCCmec typing and spa typing have the capability to characterize bacterial chromosomes and mobile genetic elements. Combination of these molecular typing methods is necessary as each method has its own advantages with respect to discriminatory power, rapidity, cost effectiveness, reproducibility, and ease of performance.

Detection of disinfectant-resistant gene inStaphylococcus aureus / 中国感染与化疗杂志

Objective To detect the disinfectant-resistant geneqacA/B in the strains ofStaphylococcous aureus isolated from January 2014 to December 2014.Methods Fifty-one isolates were collected. PCR assay was used to detectmecA gene andqacA/B gene in the isolates followed byStaphylococcus protein A (spa) typing. Antimicrobial-resistant phenotypic typing was conducted to analyze the homology of theseqacA/B positive strains. The clinical information of the patients from whom the strains were isolated was collected to further understand the clinical background ofqacA/B-carryingS. aureus.Results The prevalence ofmecA and qacA/B genes was 21.6% (11/51) and 13.7% (7/51), respectively in the strains. The prevalence ofqacA/B gene in the methicillin-resistantS. aureus strains (54.5%, 6/11) was signiifcantly higher than that in the methicillin-sensitiveS. aureus strains (2.50%, 1/40). The prevalence ofmecA gene inqacA/B gene positive strains (6/7) was signiifcantly higher than that inqacA/B gene negative strains (1/7). TheseqacA/B positive strains were classiifed into 4 spa types (t037, t091, t932 and t895). The main type was t037 (4/7), which was from the pediatric ward.Conclusions The prevalence ofqacA/B gene is low in theS. aureus strains. However, the prevalence of this gene in methicillin-resistantS. aureus strains is far higher than that in methicillin-sensitiveS. aureus. spa type t037 may be a prevalent clone in pediatric ward.

Characteristics of antimicrobial resistance and molecular epidemiology of Staphylococcus aureus isolated from patients in intensive care units / 中国感染控制杂志

Objective To study the characteristics of antimicrobial resistance and molecular epidemiology of Staphylococcus aureus (S .aureus)in the intensive care units(ICUs)of a hospital.Methods Clinical isolates of S .aureus collected from ICUs between January and December 2014 were identified and performed antimicrobial susceptibility testing,then typed by staphylococcal protein A (spa)typing and multilocus sequence typing (MLST) methods.Results Of 160 isolates of S .aureus ,120 (75.00%)were methicillin-resistant S .aureus (MRSA). Resistance rates of MRSA to erythromycin,clindamycin,and levofloxacin were all > 80%;methicillin-sensitive S .aureus (MSSA)were sensitive to cefazolin,resistance rates to erythromycin,clindamycin,and levofloxacin were 62.50%,35.00%,and 10.00% respectively.spa typing and MLST results showed that the main types of 120 isolates of MRSA were ST239-t030,ST239-t037,and ST5-t2460,the major epidemic strains were ST239-t030 (n=105,87.50%),and were isolated from 8 ICUs;MSSA had more types,ST59-t437 were detected only from depart-ment of neurology(n =8)and department of digestive diseases(n =2),ST6-t701 ,ST398-t3625,ST398-t1793,and ST121-t2092 were isolated from departments of neurology(n=7),anesthesiology(n=5),neurosurgery(n=4),and cardiac surgery(n=4)respectively.Conclusion Isolation rate of MRSA in ICUs in this hospital is high,ST239-t030 is the main type,which prevailed in hospital;different types of MSSA have epidemic trends in various departments.

Staphylococcus aureus nasal carriage among outpatients attending primary health care centers: a comparative study of two cities in Saudi Arabia and Egypt

Epidemiological and molecular data on community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) are still scarce in both Egypt and Saudi Arabia. There is almost no data regarding methicillin resistant Staphylococcus aureus (MRSA) prevalence in both countries. This study was conducted to investigate the prevalence and molecular epidemiology of S. aureus and MRSA nasal carriage among outpatients attending primary health care centers in two big cities in both countries. A total of 206 nasal swabs were obtained, 103 swabs from each country. S. aureus isolates were characterized by antibiotic susceptibility, presence of mecA and PVL genes, SCCmec-typing and spa typing, the corresponding Multi locus sequence typing clonal complex was assigned for each spa type based on Ridom StaphType database. MRSA was detected in 32% of the Egyptian outpatients while it was found in 25% of the Saudi Arabian outpatients. All MRSA isolates belonged to SCCmec type V and IVa, where some isolates in Saudi Arabia remained nontypeable. Surprisingly PVL+ isolates were low in frequency: 15% of MRSA Egyptian isolates and 12% of MRSA isolates in Saudi Arabia. Two novel spa types were detected t11839 in Egypt, and t11841 in Saudi Arabia. We found 8 spa types among 20 isolates from Egypt, and 12 spa types out of 15 isolates from Saudi Arabia. Only two spa types t008 and t223 coexisted in both countries. Four clonal complexes (CC5, CC8, CC22, and CC80) were identified in both Egypt and Saudi Arabia. However, the data collected lacked a representation of isolates from different parts of each country as only one health center from each country was included, it still partially illustrates the CA-MRSA situation in both countries. In conclusion a set of control measures is required to prevent further increase in MRSA prevalence.

Phenotype and genotype of antimicrobial resistance on nasal Staphylococcus aureus isolates from healthy people / 中华流行病学杂志

Objective To investigate the antimicrobial susceptibility and molecular nature related to the resistance on macrolides from nasal Staphylococcus (S.) aureus isolates among healthy people.Methods A total of 100 S.aureus isolates collected from 2009 to 2011 were tested for antimicrobial susceptibility by E-test.Double disc test (D-test) was used to detect the inducible clindamycin resistance.All S.aureus isolates were characterized by spa typing.Macrolides resistance genes were detected and compared with isolates that were collected clinically or from the livestock.Results High resistance rates on erythromycin or clindamycin was noticed,with 52％ and 27％,respectively.Inducible clindamycin resistance was identified in 29 of the 100 (29％) isolates.In total,the 100 isolates were assigned to 35 spa types.The most common spa types were found to be t189,t571,t002,t796,t437,t034 and t701,that accounted for 51.0％ of all the isolates.erm (C) (57.7％) and erm (B) (34.6％) were found as the dominant genes in 52 S.aureus isolates from healthy people.On the other hand,erm (A) and erm (C) were identified in 95.0％ S.aureus isolates from patients and all the livestock,respectively.Conclusion erm (C) and erm (B) carrying S.aureus strains were circulating in healthy people and these genes were distributed in different S.aureus clones.

spa typing and resistance profile of Staphylococcus aureus isolated from clinical specimens / 中国感染与化疗杂志

Objective To study the resistance and molecular profiles of Staphylococcus aureus strains isolated from the clinical specimens.Methods Antimicrobial susceptibility was tested with 56 strains of Staphylococcus aureus isolated from a hospital from May to November 2011.The mecA and pvl genes were detected.The spa genetic types were analyzed.Results A total of 21 (37.5%)Staphylococcus aureus strains were resistant to methicillin (MRSA)and 35 (62.5%)were sensitive to methicillin (MSSA).Nineteen of the 21 (90.5%)MRSA strains carried mecA gene.Compared with MSSA,MRSA were much less sen-sitive to rifampin,fluoroqunolones,tetracycline and gentamicin (P <0.05).All the MRSA isolates were susceptible to vanco-mycin,linezolid,tigecycline,quinupristin-dalfopristin and nitrofurantoin.Six spa types were identified among the MRSA strains.Type t030 was the most prevalent,accounting for 66.7% (14/21)of all the MRSA strains.MRSA-t030 and MRSA-t002 were resistant to multiple antibiotics.Eighteen spa types were identified among the MSSA strains.Type t189,t377 and t034 were the top three spa types of MSSA,accounting for 14.3%,14.3% and 11.4%,respectively.A new MSSA spa typ-ing strain new1 was isolated from pus.There were five Panton-Valentine leukocidin (PVL)-positive isolates,3 of which was MSSA-t189 type. Conclusions Type t030 is the most prevalent spa type among clinical MRSA strains,which is resistant to many kinds of antibiotics and widely spreads in the hospital setting.There are many different spa types a-mong the MSSA strains.Type t389,t377 and t034 are the top three spa types of MSSA.

Molecular typing and drug resistance of methicillin-resistant Staphylococcus aureus in Zhejiang province / 中华临床感染病杂志

Objective To investigate molecular types and drug resistance of methicillin-resistant Staphylococcus aureus (MRSA) in Zhejiang province.Methods One hundred and fourty-seven clinical MRSA isolates were collected from 11 grade A tertiary hospitals during January 2009 and December 2010 in Zhejiang province.Minimal inhibitory concentrations (MICs) of 13 antimicrobial agents were determined by agar dilution.Multilocus sequence typing (MLST),staphylococcal cassette chromosome mec (SCCmec) typing and spa typing were used to examine the homology of the strains,and drug resistance patterns were compared among different molecular types.Simpson index was used to determine the discriminatory power of three typing methods.Results Fourteen STs were identified in 147 MRSA isolates,of which ST239 (75 isolates),ST5 (24 isolates) and ST59 (23 isolates) were the most prevalent clones.Four SCCmec types (types Ⅱ to Ⅴ) were identified in 141 isolates,and 6 isolates were not typed.SCCmec type Ⅲ was the predominant type (76 isolates),which was followed by type Ⅳ (32 isolates),type Ⅱ (24 isolates) and type Ⅴ (9 isolates).All MRSA isolates yielded 23 spa types,in which t030 (57 strains),t437 (17 strains),t002 (15 strains) and t037 (12 strains) were the predominant spa types.MRSA strains were sensitive to linezolid,teicoplanin,vancomycin and norvancomycin,but were highly resistant to other antibacterial agents,especially in strains carrying clone ST239 or of SCCmec type Ⅲ.The discriminatory power of MLST,SCCmec and spa typing were 0.6885,0.6577 and 0.8165,respectively.Conclusion The predominant clone of MRSA strains in Zhejiang province was ST239-SCCmec Ⅲ-t030-MRSA,and these strains are highly resistant to most antibacterial agents,so that the surveillance of MRSA in hospital should be strengthened.

Caracterización genotípica de Staphylococcus aureus resistente a la meticilina prevalente en hospitales de Pakistán / Genotypic characterization of prevalent methicillin resistant Staphylococcus aureus in Pakistani community hospitals / Caracterização de Staphylococcus aureus resistente à meticilina prevalecente em hospitais da comunidade no Paquistão

El gen de la proteína A se usó como marcador genético para la caracterización de aislados de Staphylococcus aureus resistentes a la meticilina (SAMR). De un total de 130 aislados de Staphylococcus aureus, 90 fueron identificados como SAMR y 81 de éstos se pudieron caracterizar por tipificación spa. Todos estos aislados fueron obtenidos de cinco Hospitales Nacionales de la Comunidad. Se utilizaron dos juegos diferentes de cebadores para amplificar la región-X del gen de la proteína A en las cepas de SAMR. Un conjunto de cebadores, spa-F/spa-R ha identificado tres tipos de repeticiones diferentes, a saber, 7 repeticiones (spa 2), 8 repeticiones (spa 3) y 10 repeticiones (spa 4) y otro conjunto de cebadores, spa-1113F/spa-1514R ha identificado 4 tipos de repeticiones diferentes, a saber, 6 repeticiones (spa 1), 15 repeticiones (spa 6), y 17 repeticiones (spa 7) y 19 repeticiones (spa 8). Se identificó la repetición 11 (spa 5) con ambos conjuntos de cebadores. Los tipos de SAMR esporádicos que portaban las repeticiones 6, 7, 10, 17 y 19 fueron poco prevalentes mientras que los SAMR epidémicos con 8, 11, y 15 repeticiones fueron más prevalentes y se los consideró involucrados en la transmisión entre los pacientes dentro de los diferentes hospitales. Este trabajo concluye que la técnica spa es lo suficientemente eficiente como para diferenciar las cepas epidémicas, esporádicas y aquéllas que se transforman lentamente de esporádicas a epidémicas.

Protein A gene was used as a genetic marker for the characterization of Pakistani methicillin resistant Staphylococcus aureus (MRSA) isolates. Out of a total of 130 Staphylococcus aureus isolates, 90 were identified as MRSA and of these 90 MRSA, 81 MRSA isolates were characterized by spa typing. All of these isolates were collected from five National Community Hospitals. Two different sets of primers were used to amplify the X-region of Protein A gene in MRSA strains. One set of primers i.e, spa-F/spa-R identified three types of different repeats viz., 7 repeats (spa 2), 8 repeats (spa 3) and 10 repeats (spa 4) and another set of primers i.e. spa-1113F/spa-1514R identified 4 types of different repeats viz., 6 repeats (spa 1), 15 repeats (spa 6), and 17 repeats (spa 7) and 19 repeats (spa 8). Repeat 11 (spa 5) was identified with both sets of primers. Sporadic MRSA types carrying 6, 7, 10, 17 and 19 repeats were less prevalent, while the epidemic MRSA with 8, 11 and 15 repeats were more prevalent and considered to be involved in transmission among the patients within different hospitals. Research work concludes that spa technique is efficient enough to differentiate spa strains carrying variations in general and those slowly transforming from sporadic to epidemic outbreak in particular.

O gene da proteína A foi usado como marcador genético para a caracterização de isolados de Staphylo­coccus aureus resistentes à meticilina (SAMR). De um total de 130 isolados de Staphylococcus aureus, 90 foram identificados como SAMR e 81 destes puderam se caracterizar por tipificação spa. Todos estes isolados foram obtidos de cinco Hospitais Nacionais da Comunidade. Utilizaram-se dois jogos diferentes de cevadores para amplificar a região-X do gene da proteína A nas cepas de SAMRUn conjunto de ce­vadores, spa-F/spa-R tem identificado três tipos de repetições diferentes, a saber, 7 repetições (spa 2), 8 repetições (spa 3) e 10 repetições (spa 4) e outro conjunto de cevadores, spa-1113F/spa-1514R tem identificado 4 tipos de repetições diferentes, a saber, 6 repetições (spa 1), 15 repetições (spa 6), e 17 repetições (spa 7) e 19 repetições (spa 8). Foi identificada a repetição 11 (spa 5) com ambos os conjuntos de cevadores. Os tipos de SAMR esporádicos que tinham as repetições 6, 7, 10, 17 e 19 foram pouco prevalecentes enquanto que os SAMR epidêmicos com 8, 11, e 15 repetições foram mais prevalecentes e são considerados envolvidos na transmissão entre os pacientes dentro dos diferentes hospitais. Este trabalho conclui que a técnica spa é o suficientemente eficiente como para diferenciar as cepas epidêmicas, esporádicas e aquelas que se transformam lentamente de esporádicas em epidêmicas.

Distribution of Virulence Genes in spa Types of Methicillin-resistant Staphylococcus aureus Isolated from Patients in Intensive Care Units / 대한진단검사의학회지

BACKGROUND: Various virulence factors and superantigens are encoded by mobile genetic elements. The relationship between clonal background and virulence factors differs in different geographic regions. We compared the distribution and relationship of spa types and virulence genes among methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from a tertiary hospital in 2000-01 and 2007-08. METHODS: In 2000-01 and 2007-08, 94 MRSA strains were collected from 3 intensive care units at a Korean tertiary hospital. We performed spa typing and multiplex PCR for 19 superantigen genes. RESULTS: Relatively frequent spa types were t037 (40.5%), t002, t601, and t2138 in 2000-01, and t2460 (43.9%), t002, t037, t601, t324, and t2139 in 2007-08. We identified 4 novel spa types, 2 of which were designated as t5076 and t5079. Superantigen profiles were closely linked to spa types. For example, sea, sek, and seq superantigen genes were mainly detected in t037 strains. CONCLUSIONS: Major spa types differed depending on study periods, and the distribution of superantigen genes correlated with spa type.

spa typing and enterotoxin gene profile of Staphylococcus aureus isolated from bovine raw milk in Korea

Staphylococcus aureus is a major etiological pathogen of bovine mastitis, which triggers significant economic losses in dairy herds worldwide. In this study, S. aureus strains isolated from the milk of cows suffering from mastitis in Korea were investigated by spa typing and staphylococcal enterotoxin (SE) gene profiling. Forty-four S. aureus strains were isolated from 26 farms in five provinces. All isolates grouped into five clusters and two singletons based on 14 spa types. Cluster 1 and 2 isolates comprised 38.6% and 36.4% of total isolates, respectively, which were distributed in more than four provinces. SE and SE-like toxin genes were detected in 34 (77.3%) isolates and the most frequently detected SE gene profile was seg, sei, selm, seln, and selo genes (16 isolates, 36.3%), which was comparable to one of the genomic islands, Type I nuSabeta. This is a first report of spa types and the prevalence of the recently described SE and SE-like toxin genes among S. aureus isolates from bovine raw milk in Korea. Two predominant spa groups were distributed widely and recently described SE and SE-like toxin genes were detected frequently.